Developing devices are mounted to image forming apparatuses, such as copying machines and printers, which form images on paper sheets by electrophotography. In the developing device, a storage chamber in which developer such as toner is stored is provided. In the storage chamber, for example, a developing roller, and a conveying member that conveys the developer to the developing roller are provided. The developing roller and the conveying member are driven by driving force from a motor or the like. In a case where the developer is stored in the storage chamber, the conveying member conveys the developer toward the developing roller, and the developing roller contacts with the conveyed developer and rotates, to hold the developer on the surface thereof.
In recent years, the image forming apparatus is shipped in a state where the storage chamber is vacant without storing developer in the storage chamber of the developing device. Therefore, a user needs to mount, to the image forming apparatus, a developer container, for initial supply, having developer stored therein, so as to supply the developer from the container into the storage chamber when the user uses the image forming apparatus for the first time. In general, the developer container is called a toner container or a toner cartridge. Further, a supply operation for supplying developer at the start of use is called toner installation or setup. Hereinafter, the supply operation is referred to as toner installation.
The toner installation is performed until a state where a toner image can be developed by the developing device is reached. Specifically, the toner installation is performed until a developer layer is formed over the entire region of the surface of the developing roller. In this case, the conveying member is driven until the developer is spread over the entire region of the surface of the developing roller, and the developing roller is also driven until the developer layer is formed on the surface thereof. In conventional image forming apparatuses, in order to shorten a time (installation time) required from start of supply of the developer in the toner installation to completion of the toner installation, a motor is rotated at a higher rotational speed than usual to drive the conveying member at a double speed, when the developer is supplied (see Patent Literature 1).